Process of separation of the elements of air or of other gaseous mixtures by liquefaction and rectification



2 1 27 1,638,005 Aug 9 J. LE ROUGE PROCESS OF SEPARATION OF THE ELEMENTS OF AIR on OF 0mm GASEOUS mxwuass BY LIQUEFACTION AND RECTIFIGATION Filed July 21, 1922 @VENTOR B a A, ATTORNEYS Patented Aug. 2, 1927. i

UNITED STATES Y 1,638,005 PATENT OFFICE.

JEAN LE ROUGE, 0F BOULOGNE, FRANCE, ASSIGNOB TO SOCIETE, LAIB LIQUIDE CIETE ANONYKE POUR LE'IUDE ET LEXI'LOITATION DES PBOCEDES GEOBQIS CLAUDE), 0F PARIS, FRANCE.

rnooass or summon or THE ELEMENTS or am on or ornnn emous min-Um BY LIQUEFACTION 'AND NOTIFICATION.

Application filed my :1, 1m, Banal no. 370,012, and in mumawm 12, mt; r I

This invention relates to the separation accumulation of vapors rich in argon whenproducts of the liquefactionof air are treated therein. According to the patented method, the vapors are subjected to artial liquefaction by indirect contact wit cold liquid at a higher level in the column. The liquefaction is accomplished with simultaneous rectification of the liquid formed because of the backward return thereof in direct contact with the entering vapors. As a result of this operat'on the oxygen in the vapors is liquefied and a gaseous residue rich in argon is withdrawn from the column,

Tlns methoddoes not permit the recovery of all of the argon in the air treated for the reason that only a portion of the accumulated vapors are subjected tothe liquefying operation,.the balance of the vapors passing upwardly through the rectification column and escaping with the eflluent therefrom. Moreover, the liquefaction of the vapors rich in argon by indirect contact with the liquid in the column causes the vaporization of a corresponding quantity of this liquid wh'ch has the effect of interfering with the operation of the rectification column when ,the quantity of vapors rich in argon and consequently of the liquid vaporized reaches a certa n value. v

To avoid these difficulties itwoirld be possible to replace the liquid undergoing rectificat'on as a refrigerating medium by another liquid or corresponding coolin agent produced in any suitable manner an independently of the operation of the column. Nevertheless, the operation of the column would still be disturbed by withdrawal of the vapors rich in argon which form a considerable proportion of the vapors in the column. The vaporswithdrawn would no longer rise throu h the column to accoms plish-their normaf function in the rectification. 4 The object of the present invention is-the provision of a method whereb the difiiculties mentioned are overcome, t as permitting, for example, the recovery of substantially all of the argon contained in the air, treated without interfering with the operation of the rectification column. J v

Accordin -to the method of the present 'nvention, t e vapors rich in argon are withdrawn from the column, but, at the same time, these vapors are replaced by an equivalent quantity of vapors having the same composition except for the quantity of argon or gas P161] in argon which has been removed therefrom. argon constitutes a slight. proportion only of the vapors withdrawn, the replacement in the column of an equivalent quantity of vapors in which the argon or gas rich in argon has been separated does not interfere materially with the proper operation of the column and, in fact, improves it since it is possible thereby to produce purer oxygen and nitrogen. Under these conditions any quantity of vapors rich in argon may be withdrawn from the column. If the quantity withdrawn is such that it contains practically all of the argon contained in the air treated and if these vaporsare submitted to an operation which delivers the argon in a" .very pure state, it will be possible to avoid N the losses of the earlier method.

In order that the, invention may be readily understood, I have diagrammatically il lustruted in the accompanying drawing the preferred forms of apparatus adapted to the accomplishment of the desired objects. In the drawing,

gig, 1 illustrates one form of apparatus; an 4 Fig. 2 illustrates a slightly different form of apparatus.

Following the first mode of operation the vapors which are caused to rise in the primary column are the vapors which have been Withdrawn andfrom which a. part or all of the argon has been extracted. The vapors are introduced to the primary column at a convenient level where the vapors within As this argon or gas rich in the column have substantially thesame composition as the'entering vapors. The vapors withdrawn from the primary column are caused to travel outside the column through and automaticpurification which permits the liquidresulting from the rectification of the obtainin of a, as, in this. case argon, of a high egree'o purity.- Referring to F1g. 1 of the drawing, the

' vapors rich in argon is vaporized before returning to the column and this vaporization is preferably utilized for effecting rectification. The primary rectification column which may be of any suitable form is represented in this fi re onl by the lower art A includingt e liquid ox gen vaporizer B. The liquid oxygen pro need in the usual manner b the rectification of liquids and vapors in t eprimary column is vaporized in the usual manner, for example, by

the compressed cold air passing through the coil C, and the liquid formed by the liquefaction of the compressed air is delivered in the known manner by the pipe D to the ppare drawn through an auxiliary rectification per part of the primary column A.

gaseous oxygen escapes at E. The vapors rich in ar on accumulating in the lower trays of the column are withdrawn from the column A, for example, at F. These vapors column G and a temperature exchanger H by a compressor I. In the auxiliary column the vapors serve as a rectifying agent for the liquid fiowing therethrough and in the exchanger H the vapors are warmed by indimet contact withpreceding portions thereof which'are. recompressed by the compressor and returned throu h a pipe J- passing meanwhile through t e exchanger H where they are cooled b the heat interchange hereinbefore referre of a lique er-vapori zer consisting, for example, of-a bundle of tubes K having a valve L through which any residual unliquefied ggas ma escape' The liquid formed in the tubes is delivered by; a pipe M, having v a valve M, tothe upper part of the column This liquid is rectified as hereinbefore stated by contact with the vapors rich in argon rising through the column and passing to the exchanger H. y The descending liquid is thus Fenriched'in 0 gen while the, argon and nitro en content 0 the vapors increases.

The liqui "finally accumulates at N and escapes by a tube 0 forming a hydraulic seal to the vaporizer P where it surrounds the tubes K of theliquefier." The liquid'in the to. The cooled and com: pressed'va rs are delivered to the interior 1,ess,oou

drawn and Where the vapors within the column have substantially the same com position as the vapors returned thereto.

, When the compressor I is started the gases ,forced up b I the compressor and liquefied in K, and t en vapourized in the column become as is well known richer and richer in the more volatile element which in this caseis the argon mixed with a small quantity of. nitrogen. When the gases issuin from the upper part of the column G an drawn in by the compressor contain the desired quantity of argon, a portion of this gas can be withdrawn through a cock R situated between the temperature exchanger H and the compressor I, and the quantity withdrawn may be such that it contains practically all the argon which was present in the air treated in the main column A. a In this case the supply of the compressor must naturally be regulated accordingly.

With regard to the nitrogen of which very.

small quantities may exist in the gas re- I, K, M, l, Q, Y and it cannot increase in .this auxiliary circuit because the cock L permits of the elimination, in a constant manner, of the gas containing practlcall all the nitrogen entering the auxiliary co umn at'the level F.

In this mode of operation it is apparent that the vapors returned by the pipe Q to the primary column :should enter that column at Y- under a pressure equal to that existing at the point of entrance to the col-v cient to ensure the desired pressure upon'the I va ors passing through Q to the column, A,

ccordingto'another mode of o crating themethod, the gas which iscause to rise I in the primary column is derived from liq- 1 uid resulting from the rectification of the turned directly to the primary rectification .column. ,This liquid is introducedprefen ably on one of the trays directly below the level at which the vapors are withdrawn from the; primary column. The liquid thus introduced descends with. that. flowing.

argon present in the air originally treated.

, in the vaporizer B of the v p The liquid formed by this quefaction with pressure of the vapors therein as in the pre,

ceding example. c

Referring to Fig. 2 of the drawing, it will be noted that theentering'compressed air is liquefied in the vaporizer B in the known manner in two successive portions, furnish-. 'ing two liquids, one rich in oxy en and the I other. rich in nitrogen, which 'quids are delivered to the rectifying column by the pipes D, D'. The vapors rich in argon withdrawn at F are treated in the same manner as in the apparatus illustrated in Fig. 1, but the vapors returned by the compressor I are delivered by a pipe J to a bundle of tubes K, for example, of annular form immersed in the liquid rich in oxygen rimary column.

backward return in the tubes K is delivered by a pipe M to the upper part of the auxiliary rectification column G wherein it flows downwardly and is rectified by contact with the vapors rich in argon risin through the auxiliary column. he li ui accumulating as a result of this recti cation in the lower part of the auxiliary column G is delivered by a pipe X onto one of the trays in the lower part of the pri mary column.

The results accomplished are substantially identical as in the preceding embodiment of the invention. Oxygen is separated from the vapors rich in argon in the auxiliary column and nitrogen is likewise separated in the tubes K and escapes through a valve L. The vapors traveling in the cycle of the auxiliary column are progressively enriched in argon, and a portion of these vapors corresponding substantially to the amount of in the primary column A may be withdrawn through a valve R. The liquid returned to of argon or gas rich in argon withdrawn withdrawal of va the column through the pipe X furnishes -5 a quantity of vapors substantially equal to the quantity withdrawn at F less the amount through the valve R. The operation of the primary rectification column is thus carried on without interference by reason of the rs rich in ar on.

It is to be un erstood that t e methods as hereinbefore described may be varied within thescope' of the accompanying claims without departing from the invention or.

sacrificing any of the advantages thereof. 7

I claim 1. A method of separating the constitucuts of a ternary gaseous mixture liquefying at low temperatures, which comprises subjecting the gaseous mixture to a primary rectification, withdrawin therefrom a gaseous mixture impoveris ed in the most volatile constituent, introducing this mixture in the "gaseous phase to an auxiliary rectification, withdrawing the gaseous product of the auxiliary rectification, separating a portion of the most volatile constituent fromthe gaseous. product, liquefying the re .maining vapors and utilizing the liquid producedin' the auxiliary rectification. 2. A method "of separating the constituouts of a gaseous mixture 'liquefyin at low temperatures, which comprises 1su jecting thegaseous mixture to a primary rectification, withdrawing therefrom a gaseous mix-"- ture impoverished in one of the constitu-' 'ents, introducing this mixture in the gase- I one phase to an auxiliary rectification, compressing the gaseous eflluent of the auxiliary rectification, cooling it to separate another of the constituents from a liquid which is thereby impoverished in that constituent, and utilizing the impoverished liquid'as a rectifying agent in the auxiliary rectification. i

3. A method of separatin the constituents of a gaseous mixturelique ying at low tem-. peratures, which comprises subjecting the gaseous mixture to a primary rectification,

withdrawing therefrom a gaseous mixture I impoverished in one of the constituents, 'introducing this mixture in the aseous phase to an auxiliary continuing rectification, compressing the gaseous efiluent, cooling it toseparate a liquid containing chiefly two of said constituents and a residue containing chiefly a third constituent, using the separated, liquid in said auxihar rectification .and withdrawing portions'o said gaseous efiluent when it is sufiiciently enriched in the desired constituent.

4. A method of recovering argon from air,

which comprises subjecting the air to a primary rectification, withdrawing therefrom a gaseous mixture impoverished in nitrogen, introducing this mixture in the aseous phase to a continuing auxiliary recti cation, compressing the gaseous effluent, cooling'it to separate a li uid containing chiefly argon.

and oxygen an a residue containing prac tically all'of the nitrogen, using the lastnamed liquid in said auxiliary, rectification and repeating the operation.

5. A method of separating the constitucuts of a gaseous mixture liquefying at low I temperatures, which comprises subjecting the gaseous-mixture to a primary rectification, withdrawing therefrom a gaseous mix- 1 tureimpoverished in one of the constitu-' ents, introducing this, mixture in the gaseous' phase to auxiliary rectification, thereby producing a 1i uid rich in the least volatile constituent an a gaseous fraction, compressing this gaseous fraction, subjecting it fraction a residue containing the most vola tile constituent and a liquid containing chiefly two of said constituents, returning this liquid for further auxiliary rectification and repeating the operation.

.6. A. method of recoverin argon from air, which. comprises subjecting a gaseous mixture to a primary rectification, withdrawing therefrom a gaseous/mixture impoverished in nitrogen, introducing, this mixture in the gaseous phase to an auxiliary rectification, thereby producing a liquid' product rich in oxygen and a gaseous fraction, compressing this gaseous fraction, subjecting it toindirect contact with the liquid rich in oxygen to evaporate 'the latter and to simultaneously separate by liquefaction fromthe gaseous fraction a gaseous residue containing principally nitrogen and a liquid containing chiefly ar on and oxygen, returning this li uid for urther auxiliary rectification an repeating the operation.

7. A method of recovering argon from air,

which comprises subjecting a gaseous mixture to a primary rectification, withdrawing therefrom agaseous mixture impoverished in nitrogen, introducing the mixture in the gaseous phase to an auxiliary'rectification by means of a liquid containingchiefiy argon and oxygen, thereby producing a liquid product rich in oxygen and a gaseous fraction, withdrawing portions of the aseous fraction when it is sufiiciently enric ed in argon, compressing the remainder of the fraction, subjecting it to indirect contact 'with'the liquid rich in oxygen to evaporate the latter and to simultaneously separate by liquefaction from the seous fraction a residue containing principally nitrogen and a liquid containing chiefl argon and oxygen, and returning this liquid for further auxiliary rectification. a

:8. A method of recovering er on from air, which comprises subjecting .t e air to a primary rectification, withdrawing therefrom a gaseous m xture impoverished in mtrogen introducing. the mixture in the gaseous ph I subjecting the eflluent from the auxiliary;

ass to an. auxiliary rectification and .rectification to selective liquefaction to sep-' which comprises subjecting t e air to a 4 primary rectification, 'withdrawin o0 arate nitrogen therefrom, rejecting; the nitrogen and returning the liquid formed for further auxiliary rectification.

9. Amethod of recovering ar on from air,

therefroin'a gaseous mixture" impoverished in. nitrogen, introducing th1S mlXtl]1e in the gaseous phase to an (auxiliary rectification and thereafter causing the eflluent from the auxiliary rectification to travel in a closed circuit wherein it is successively subjected mascot to selective liquefaction and'to further auxiliary rectification.

10. A method of recovering argon from the atmosphere, which comprises subjecting air to a primary rectification, withdrawing therefrom a gaseous mixture impoverished in nitrogen, introducing this mixture in the gaseous phase to a cyclic operation including an auxiliary rectification to separate a liquid enriched in oxygen with recompressionand selective liquefaction of the gaseous effluent from the auxiliaryrectification to separate residual gaseous nitrogen, the remainder of said gaseous'efiluent being returned for further auxiliary rectification and thereby progressively enriched in argon.

11". A method of recovering argon from air which comprises subjecting the air to liquefaction and a primary rectification to produce a gaseous mixture enriched in argon, withdrawing this gaseous mixture, subjecting it to anauxiliary rectification in contact with a liquid rich in'argon, withdrawing the gaseous eiiluent from the second rectification subjecting it to recompression and selective liquefaction to separate residual gaseous nitrogen and to produce a liquid suitable for use in the auxi iary rectification and returning the equivalent of the gaseous mixture withdrawn from the primary rectification thereto substantially free from argon.

12. A method of recovering argon from air which comprises subjecting the air to liquefaction and a primary rectification to produce a gaseous mixture enriched in argon, withdrawing this gaseous mixture, subjecting it to an auxiliary rectification in contact with a liquid rich in argon, withdrawing the gaseous efiluent from the auxiliary rectification and. subjecting it to recompression and selective li uefaction to separate resid ual (gaseousnitrogen and to produce a li ui suitable for use in the auxiliary recti cation, evaporating the liquid product of the auxiliary rectification by the selective liquefaction of the compressed gaseous efiluent, and returnin the resulting vapors for utilization in the rst rectification.

13. A method of recovering argon from; air which comprises subjecting the air to jecting it to an auxiliary rectification in contact with a liquid rich inargon, withdrawing the aseous efiluent from the'auxiliary rectification and subjecting it to recompression and selective liquefaction to se arate residual gaseous nitrogen and to pro 11ce a liquid suitable for use in the auxiliary rectification, and returning the liquid roduct of the first rectification.

- 14. A method of separation of the con-- the auxiliary rectification for uti ization in i by liquefaction and rectification permitting extraction of a gas very rich in one of the constituents having an intermediate boiling point, for example, a gas very rich in argon in the case of air, consisting of withdrawing the vapors rich in that constituent from stituents of air and other gaseous mixtures by liquefaction and rectification permitting extraction of a as very rich in one of the constituents having an intermediate boiling point, for example, a gas very rich in argon in the case of air. consisting in withdrawing the vapors rich in that constituent from a primary rectification and treating them by a thermally remote auxiliary rectification for enrichment in gaseous argon while introducing into the rimary rectification near the level of with rawal of the vapors the same vapors which have been withdrawn and separated from part or practically all of the argon content.

16. A method of separation of the constituents of air and other gaseous mixtures by liquefaction and rectification permitting extraction of a gas very rich in one of the constituents having an intermediate boiling point, for example, a gas very rich in ar on in the case of air, consisting in withdrawing the vapors rich in that constituent from a primary rectification and treating them by a thermally remote auxiliary rectification for enrichment in gaseous argon while using in the rimary rectification vapors resulting from tfie vaporization of liquid produced'by rectification of the vapors withdrawn.

' 17. The method as in claim 14, consisting in introducing to the primary rectification preferably at a level below that at which the vapors are withdrawn the liquid formed by the rectification of the vapors withdrawn, vaporizing this liquid and utilizing the vapors in the primary rectification. 18. A method of separation of the constituents of air and other gaseous mixtures by liquefaction and rectification permitting extraction. of a gas very rich in one of the constituents having an intermediate boiling point, for. example, a gas very rich in argon in the case of air, consisting of withdrawing the vapors rich in that constituent from a primary rectification, treating the va ors in a thermally remote auxiliary recti cation for enrichment in one of the constituents and replacing in the primary rectification the equivalent of the vapors withdrawn substantially free from the constituent extracted.

19. A. method of separating the constituents of ternary gaseous mixtures, which compris is partly separating the gaseous mixture to obtain another gaseous mixture enriched in the two less volatile constituents, introducing this enriched gaseous mixture in the gaseous base to a rectification, recompressing and cooling the gaseous eflluent from the rectification and utilizing the liquid thereby produced in the rectification of further quantities of the gaseous mixture introduced.

20. A method of separating the constituents of ternary gaseous mixtures, which com rises forming a aseous mixture impoveris ed in one of said constituents by a primary rectification, withdrawing the impov-' erished mixture in the gaseous phase from an intermediate point in the primar rectification, subjecting it to a therma ly remote auxiliary rectification to further enrich the mixture in another constituent and returning the equivalent of the gaseous mixture withdrawn from the primary rectification thereto substantially free from the constituent extracted at a point adjacent to the point of withdrawal.

21. A method of separating the constituents of ternary gaseous mixtures, which comprises producing a mixture in the gaseous phase impoverished-in one of the constitucuts by a primary rectification, withdrawing the gaseous mixture, introducing it to an auxiliary rectification, recompressing and cooling the gaseous efiluent from the auxiliary rectification to further enrich the mixture in another constituent and returning the equivalent of the gaseous mixture with drawn from the primary rectification thereto substantially free from the constituent extracted at a point adjacent to the point of withdrawal.

22. A method for the separation of a mixture of gases such as air into its constituents, which consists in selectively liquefying a portion of the mixture in a condenser located at the foot of a rectification column followed by non-selective liquefaction of the remainder in a condenser also located at the foot of the rectification column and withdrawing at a selected level in the column some of the vapor undergoing rectification as it reaches that level.

In testimony whereof I afiix my signature.

JEAN LE ROUGE." 

